Photovoltaic solar panels are known which absorb solar and ultra violet rays, transforming them into electrical energy.
Referring to FIG. 1 herein, there is illustrated schematically in perspective view an installation comprising a plurality of known solar roof tiles, integrated into an existing concrete tile roof. Each solar roof tile has a width of approximately 3 concrete roof tiles. To install the solar roof tiles, rows of individual roof tiles are removed, and the solar roof tiles are fitted to the rafters of the roof in place of the concrete roof tiles. Electrical connections to the solar roof tiles are passed through the water proof membrane of the roof, and the electrical connectors at the rear of each roof tile are connected into an electrical circuit within the loft of the roof. Alternatively, the electrical connectors can be connected together on top of the water impermeable membrane, and routed to the edge of the roof, so that a single electrical cable is fitted outside the building down to an electrical junction box at ground level.
Referring to FIG. 2 herein, there is illustrated schematically in detail, part of a solar roof tile as shown in FIG. 1 herein. The solar roof tile comprises a relatively thick sheet of substrate 200, for example made of a plastic sheet, of a thickness similar to the thickness of the adjacent concrete tiles. On top of the plastic substrate, are positioned a plurality of substantially square solar panels 201. On top of the solar panels, is positioned a glass or plastics cover sheet 202, which is held to the plastic substrate by a plurality of external clips 203 around the edges of the clear transparent plastics sheet.
Referring to FIG. 3 herein, there is illustrated schematically in perspective view, a pair of solar tiles as shown in FIGS. 1 and 2.
Referring to FIG. 4 herein, there is illustrated schematically in cross sectional view part of a known photovoltaic solar panel. The solar panel 400 comprises a back sheet 401; first and second encapsulation layers 402, 403; a photovoltaic cell 404; and an ultra-violet resistant glass or plastic screen front sheet 405, which protects the panel against mechanical impact and weathering.
The back sheet portion 401, of the photovoltaic solar panel 400 comprises two surfaces 406, 407, wherein the first surface 406 may be attached to the surface of a roof tile. The second surface of the back sheet portion 407 is adjacent to a first surface 408 of encapsulation layer 402; and a second surface 409 of first encapsulation layer 402 is in adjacent contact with the photovoltaic cell 404. The photovoltaic cell is also in adjacent contact with a first surface 410 of second encapsulation layer 403; and a second surface 411 of second encapsulation layer 403 is in adjacent contact with a first surface 412 of the front sheet 405.
The term “adjacent contact with” does not necessarily mean that the second surface of the encapsulation layer is in contact with a surface of the photovoltaic cell. A layer of encapsulation material may be used between the photovoltaic cell and the back sheet 401 and/or the front sheet 405
Polyethylene terephthalate PET is a known encapsulation material, which is used in solar panels to bond front and back sheets of the panel together by the process of lamination.
Lamination of solar cells with polyethylene-vinyl acetate films is conducted at about 150° C., and permits molten polyethylene-vinyl acetate to flow into voids in a solar panels to encapsulate the solar cell.
The current lifespan of PET solar panels is in the region of 5 to 10 years.
Known photovoltaic panels do not integrate well into the architecture of older, traditional buildings.